You probably know the story. This week the supreme court told Nicolas Granatino that a "marriage contract" he signed in 1998 before marrying Katrin Radmacher, and then challenged after their divorce, had "decisive weight". The German heiress gets to hang on to the bulk of a £100m fortune. Step back from the specific details of this case, though, and it is hard not to feel some regret at the new status given to prenuptial agreements. Doubtless there are matrimonial lawyers in well-furnished offices in enviable postcodes who are celebrating this ruling. Before them lies the handsome prospect of a booming business to be made out of negotiating and arranging prenups and then enforcing them in court. But others will not be celebrating. Among them will be Lady Brenda Hale. She was the only supreme court judge to oppose the ruling, arguing that it was "inconsistent with the continued importance attached to the status of marriage". And she is right, because while marriage is at one level a contract, it is meant to be much more than that. Marriages are forms of social commitment, too, and also expressions of faith that they will endure for decades. From the donation of blood to friendships to marriages, people seek out relationships for something far bigger than small print. To start off any marriage by planning for its failure – and the material consequences of that breakup – is to erode the basis of that relationship at the outset. Practical? Maybe. Regrettable? Certainly.